[time-nuts] Homebrew frequency counter, new board test result

[Li Ang]

Hi
    It's me again. I was debugging the new FPGA version board this week.
The attached file is the test result of this new board, and 2 tests of CPLD
version(2014/12/11) are also included. There are few things changed between
these 2 version:
1) CPLD -> FPGA
2) XC6206 -> TPS79333 for TDC power supply. Analog and digital part of TDC
use dedicated LDO.
3) 2 layer -> 4 layer
4) add 74ALV2G14 since FPGA does not support schmitt input

A little bit better than before. :)



mistakes of current version:
1) the board is 1cm bigger than expected.......
2) the themral pad of FPGA should be connected to ground

test instruments
1) HP6622A as power supply
2) FE5650 rb as reference
3) PRS10 rb as DUT



Li Ang
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